Weird Noise

[Glasswarrior]

I've owned a 2003 D4D T Spirit Avensis for 18 months now. It has 107000 miles on and apart from the previous problem (warning lights) has given no trouble and drives well. There has been, though, a noise that seems only to begin at around 35-38 mph and sounds like a low hum/whine under the usual road noise & general sounds of the car. It sometimes seems to come from the front and often seems like it comes from the middle of the car and sounds like a wheel bearing wearing out but doesn't seem distinct enough and doesn't seem to increase much with speed, it just seems to stay the same above 40mph and sometimes fades away around 60+.

It's been around for quite a few months now, never getting worse. I put two new front tyres on last week and the sound seemed to change, seeming to move towards the middle of the car though if I sit in the back when my wife drives I usually can't hear it. The two rear tyres are the ones I bought the car with and are two different brands. I had an earlier Avensis before this one and experienced something similar as the tyres wore to near their replacement point and the noise disappeared when I replaced all four.

The car is GB registered (originally from Inchcape Toyota in Oxford) and had it's first Northern Ireland MOT earlier this year. Part of that is checking for worn wheel bearings and nothing was pointed out. I have jacked up each wheel and tried them for wobble but each seem sound. No one wheel seems to get hotter than another (something I experienced a long time ago with a definite worn bearing) and there are no discernible adverse affects on driving. steering etc. The sound doesn't seem to get worse if steering one way or another.

Has anyone experienced anything similar or perhaps know what may be the cause? Could it be a bearing or something else or just tyre noise? My wife doesn't hear the noise and neither do either of my children and we are all in the car regularly. Can anyone suggest any other checks I could do before resorting to a mechanic? I'm fairly mechanically competent.

Any insight greatly appreciated.

Thank you.

[bestseany]

Sounds like it could be a gearbox bearing. Does it sound louder on the overrun? (when you let your foot of the accelerator and coast)

The gearbox bearings are an Avensis weak point.

[Glasswarrior]

Sounds like it could be a gearbox bearing. Does it sound louder on the overrun? (when you let your foot of the accelerator and coast)

The gearbox bearings are an Avensis weak point.

Thanks for the reply. It actually doesn't sound louder on the overrun. Any other ways I can test for this and is it an expensive job?

cheers

[bestseany]

Not sure of a way to test it really other than taking things apart and checking. If it is that then it's a gearbox rebuild or replacement I'm afraid.

To be honest though, if it isn't getting worse then I wouldn't bother.